What began as a competition to appease a member of royalty's birthday wishes, continued on to not only introduce an entirely new area of mathematical studies but also to leave one particular question to remain without a complete and substantiated...
Let X and Z be topological spaces and Y be a subspace of X. A con-
tinuous function f : Y ! Z is extendable to X if there exists a continuous
function f : X ! Z such that f(x) = f(x) for all x 2 Y . If every continuous
function f : Y ! Z is...
